1. Field of the Invention
The present invention relates to optical communication systems and, more specifically, to monitoring the performance of such systems.
2. Description of the Related Art
Fiber optic networks are widely used for data transmission in modern communication systems. Due to increasing data traffic volumes, monitoring and management of networks become increasingly important. For example, such monitoring may include a measurement at a particular point in the network of the quality of an optical signal corresponding to one or more optical communication channels. The optical signal may be analyzed for various impairments, e.g., optical signal-to-noise ratio (OSNR), timing jitter, chromatic dispersion, and the like. Obtained information may then be used to improve the performance of the network, for example, if certain impairments exceed a tolerable level.
One known method of analyzing an optical signal is to tap that signal, convert it into an electrical signal using an optical-to-electrical (O/E) converter, and then analyze the electrical signal for impairments using electrical signal-processing methods. However, one disadvantage of this method is that it typically requires high-speed electronics. Optical methods applied to optical performance monitoring have certain advantages over purely electrical methods because at least part of the signal processing is accomplished in the optical domain, which reduces bandwidth requirements to the monitoring electronics. While nonlinear optical techniques are particularly suitable for optical performance monitoring, practical applications of such techniques to optical performance monitoring are not yet sufficiently developed.